Has the Dakota Cub fuel valve changed your fuel management?

[Gilbert Pierce]

This label contains a note "Single tank operation prohibited if tank contains less than 5 gal". I don't think mine has this note. Why is this note provided?

After learning that the tanks don't feed equally, I have reverted to running left or right most of the time. On a long flight it's comforting to know how much is in each tank. Do I need to reconsider this practice?

Dean, you just stated the reason I personally have no desire for a BOTH position.

[Tp109]

I flew a 22 with a maule weatherhead valve with the both position, if I took off with a full left tank and nothing in the right tank, within a half hour most of the fuel would be in the right tank, I could not figure it out, it simply wanted all the fuel in the right tank. I flew coordinated and wings level, gave up, I went back to a Left and Right only valve, like that better anyway, two positions and the handle is not jabbing my knee in either one.

[ysifly2]

I do not have the Dakota valve. I have the original fuel system. But if I did I would run the tanks individually R L
I like to know what I have & where I have it. I only take off on the R tank when it is full. I run the right tank in cruise flight and usually land and take off on L
I have run the R tank completely dry in flight but do not do that as a general practice.
AL

Even with the DC valve, on the flight I noted above, I still switch tanks after discrete times. My practice is 30 minute increments as follows: L-R-L-R-L, then switch again to R and run until I calculate (anticipate) it to be empty, which then helps validate my fuel flow rate, then switch to the Left and with the confirmed (calculated) fuel rate of the right tank I now have a fairly accurate time to empty. This would be if I am going for maximum range, gives me a time element to cross check against the fuel gauge ( not that I trust it, but it is an indicator) and fuel computer fuel flow... against the fuel I measured to be in the tanks at launch.

I haven't flown much extended time on the Both selection, maybe an hour, so do not have data to determine how balanced (or not) of the flow rate between the two tanks in that setting.


Bryan

[dhillier]

Is there any discount to be gained from Dakota Cub for Shortwingpiper.org members at present?

[deandayton]

I called Dakota Cub (I think I talked to Brian?) and asked about the uneven fuel flow. I also asked about the placard prohibiting running on a single tank with less than 5 gallons. He seemed surprised when I told him that I have seen as much as 10 gallons difference between right and left tanks. The only reason given for the single tank restriction is to comply with the Piper right tank restrictions. I asked if I could remove their placard as long as I complied with the Piper placard, of course he said NO.

He expressed concern that I might have a partial blockage from the right tank and suggested a flow check. Here are the results. Starting with 8 gallons per side I drained approx 3 gallon per side (actually I eyeballed about 3 gal in a 5 gal can). Right side took 7 minutes (25 gph), left side took 5 minutes (36gph). Obviously plenty of flow, but does the fuel line routing account for this much difference? Does anyone else have fuel flow measurements they can share?

Yes, I checked the cap vents. They are clear and removing the cap didn't seem to change flow rate.

I kept draining until the left tank was almost empty and I could see that the right tank was feeding with about 4 gal left in the tank. Just watching the stream, I didn't see any change in flow.

I'm still disappointed with the uneven feeding and the restriction on use of single tanks, but I don't think there is a fuel fuel flow problem with using the both position. Anyone else have an opinion?

[Steve Pierce]

We had the same issue with uneven fuel flow in the Super 20 Pacer with the slotted wings that Dakota Cub built. The fuel line routing is the issue. You have a door on the left and the right side so there is no direct route for the right tank. Same issue on my Super Cub but getting down to 5.5 gallons I still not not disrupt fuel flow. The STC for Both System on the Super Cub requires an additional fuel line added to the right tank and the positive pressure fuel caps but they still don't have the obstruction of the rear door messing up direct routing of the rear fuel pickup in the right fuel tank.

[mmoyle]

Wonder what mine will be with the Trimmer Maule fuel valve and seaplane doors?


Sent from my iPad using Tapatalk

[piperrocks2013]

Wonder what mine will be with the Trimmer Maule fuel valve and seaplane doors?


Sent from my iPad using Tapatalk

Little off topic but thought you guys might find this interesting. I had bad fuel on one tank but due to the circumstances I didn't trust the fuel on the right side either so I drained the old gas by disconnecting it at the gascolator and hooking up a 3/8 clear hose to a jerry cans. I have notice this on couple PA22 in the past. Right Tank has more bubbles in the line the then the left. Which I could see if banked hard on low tanks I could see a problem arising. Also after draining and refueling the tanks I hooked the line back to the Gascolator and disconnected it at the carb and hooked up clear line and watched my fuel flow. 54 GPH on the left and about 46 on the right. Thought it was kind of interesting.


Cheers

Jared

[Stephen]

Wonder what mine will be with the Trimmer Maule fuel valve and seaplane doors?


Sent from my iPad using Tapatalk

This is how mine is set up plus I have Dakota 24 gallon tanks. I run on both almost all the time with no problems. I never think about switching as they feed reasonably even. I have sight gauges and avoid running much below 1/4 tanks. Just make sure your gauges (even sight gauges) are calibrated correctly. We don't have fuel at my home base so I often put fuel in one tank and let them even out. Forgetting to switch tanks will wake you up.

[deandayton]

I think I've found why the right tank is not flowing when using the both position. The gasket on the right cap is a little thicker, this is causing it to partially block the vent holes around the edge of the cap. The left side appears to have the same problem but not as bad. I replaced the gasket on the right side with a smaller gasket that does not cover the holes and now the right side drains faster than the left.

Oh well. I already ordered a new set of F Atlee Dodge caps before I figured this out. Hopefully the new caps will eliminate the tendency to get water in the tanks during a heavy rain.